Is It Safe to Drill Through Asbestos Cement Sheeting in My Garage?

Drilling through asbestos cement (AC) sheeting is not recommended as a casual DIY task — and in many situations it is outright dangerous. While bonded asbestos cement is considered lower-risk than loose or friable asbestos, drilling, cutting or grinding it releases fine asbestos fibres into the air that can cause serious, irreversible lung diseases including mesothelioma and asbestosis. Here's what every NZ homeowner needs to know before picking up a drill.

What Is Asbestos Cement Sheeting?

Asbestos cement (AC) sheeting — sometimes called fibrolite or super six — was widely used in New Zealand homes, garages, and farm buildings from the 1940s through to the late 1980s. It was used for wall linings, roofing, eaves, soffits, and fencing. If your garage was built before 1990, there is a real chance the flat or corrugated sheeting contains asbestos.

Asbestos cement is a bonded (non-friable) material, meaning the asbestos fibres are locked into a cement matrix. In good, undisturbed condition it poses a relatively low risk. However, the moment you drill, cut, sand, or break it, fibres are released — and that's when it becomes hazardous.

The Health Risks of Disturbing Asbestos

Asbestos fibres are microscopic and invisible to the naked eye. Once airborne, they can be inhaled deep into the lungs where they remain permanently. Long-term exposure — or even short, intense exposure — is linked to:

• Mesothelioma (a rare but fatal cancer of the lung lining)
• Asbestosis (progressive scarring of lung tissue)
• Lung cancer

There is no safe level of asbestos fibre exposure. Symptoms of asbestos-related disease can take 20–40 years to appear, which is why many New Zealanders are still being diagnosed today from work done decades ago. WorkSafe NZ has detailed guidance on asbestos health risks and legal duties.

NZ Legal Requirements for Asbestos Work

Under the Health and Safety at Work (Asbestos) Regulations 2016, asbestos removal work in New Zealand is tightly regulated:

• Class A removal (friable asbestos or more than 10 m² of bonded asbestos) must be carried out by a licensed Class A asbestos removalist.
• Class B removal (bonded asbestos up to 10 m²) must be carried out by a licensed Class B removalist (or Class A).
• Homeowners doing work on their own homes are not automatically exempt — if the work disturbs asbestos, the regulations still apply in a workplace context, and even in a domestic setting the health risks are identical.

In practice, drilling a single hole may fall below the 10 m² threshold, but the risk to you, your family, and neighbours remains real regardless of the legal threshold. Always check with WorkSafe NZ if you are unsure about your obligations.

How to Identify Asbestos Cement Sheeting

You cannot identify asbestos by looking at it. The only reliable method is laboratory testing. If your garage was built before 1990, treat any flat or corrugated fibre cement sheeting as potentially containing asbestos until proven otherwise.

A licensed asbestos assessor can take a sample safely and have it tested by an accredited laboratory. This is the recommended first step before any drilling, renovation, or demolition work.

What You Should (and Shouldn't) Do

Do:

• Assume it contains asbestos if the building predates 1990
• Have the material tested by a professional before disturbing it
• Keep the area well ventilated and limit access if sheeting is damaged
• Hire a licensed asbestos removalist for any work that disturbs the material
• Check MBIE Building Performance for guidance on building consent requirements if you plan to remove or replace sheeting

Don't:

• Drill, cut, sand, grind, or break AC sheeting without professional advice
• Use a high-speed angle grinder or power saw on suspected asbestos material
• Sweep up dust or debris dry — this re-suspenses fibres
• Dispose of asbestos material in your general rubbish — it must go to an approved facility

If You Must Drill — Strict Precautions Apply

If a licensed professional has confirmed the sheeting is asbestos cement and a small number of holes are genuinely unavoidable, WorkSafe NZ guidance outlines strict control measures. These include:

• Using a sharp, slow-speed drill (not a hammer drill) to minimise dust
• Wetting the area thoroughly before and during drilling to suppress fibres
• Wearing a properly fitted P2 respirator (not a dust mask)
• Using disposable coveralls and gloves
• Collecting and double-bagging all waste for disposal at an approved facility
• Never dry-sweeping the area

Even with these precautions, this work is best left to a licensed professional. The cost of hiring a qualified asbestos removalist is far less than the long-term health consequences.

When to Call a Professional

Call a licensed asbestos removalist if:

• You suspect your garage sheeting contains asbestos and you need to drill, fix, or remove it
• The sheeting is damaged, crumbling, or weathered
• You are planning a renovation or demolition that will disturb the material
• You need an asbestos management plan for a rental property (required under the Healthy Homes Standards)

You can find licensed asbestos removal specialists and assessors in your area on tradedirectory.co.nz. Always ask to see their WorkSafe licence before work begins.

Sources & Further Reading

• WorkSafe NZ – Asbestos
• MBIE Building Performance – Building Code
• BRANZ – Asbestos in homes
• Tenancy Services – Healthy Homes
• Standards NZ